Robert Norman and Richard Wells
Department of Kinesiology Faculty of Applied Health Sciences University of Waterloo Waterloo, ON N2L 3G1
For the Institute for Work & Health To the Royal Commission on Workers Compensation in British Columbia
Ergonomic Interventions for Reducing Musculoskeletal Disorders: An Overview, Related Issues and Future Directions. Robert Norman and Richard Wells
In most industrialized countries, the costs of compensation for musculoskeletal disorders account for at least one half of all workers compensation costs and recent reviews have reaffirmed that a strong work-related component exists for many upper limb and low back pain cases. A combination of physical, psychological, and psychophysical workplace risk factors have been documented. Risk factors for the development of low back pain include (moderately) flexed, laterally bent or twisted trunk postures, high forces on the hands, high one time or accumulated forces on the spine, and vibration. Similar workplace physical risk factors are associated with high levels of musculoskeletal disorders in the neck, shoulders and arms. Physical risk factors such as high forces, high repetition, working with arms overhead, long term static postures, local contact forces and vibration are commonly identified. Psychological risk factors are found regardless of whether the problem is upper limb, low back or elsewhere. They include perceptions of low control and poor workplace social environment, and perceptions of high physical demands whether measured to be high or not. There is conflicting evidence on the role of job satisfaction as a risk factor. Reduction of these risk factors is the goal of most preventive approaches. The work-related portion of the injuries and resulting disability is potentially preventable and it is important to identify interventions for reducing work-related musculoskeletal disorders (WMSD). There are many approaches to intervening in the workplace to reduce initial incidence (primary prevention) and disability (secondary prevention). For example workstation design changes, employee training, back schools, wrist splints and back belts, job rotatation and stress management are commonly used approaches. The purpose of this Chapter is to review the evidence for (or against) the utility of ergonomic interventions. The Chapter will not be an epidemiological review of intervention studies but, rather, it will map out the issues in intervention to prevent musculoskeletal disorders, summarize the literature which bears upon these issues and suggest issues that must be addressed in the future.
Ergonomic interventions are commonly classified as engineering, administrative or behavioural/ personal. Rigorous evaluation of effectiveness of interventions is, however, difficult for methodological and organizational reasons and research reported on many interventions does not reach usually accepted levels of scientific quality. Despite this, the following conclusions appear warranted: For primary prevention, engineering interventions appear to reduce exposure to risk factors (efficacy) but the literature does not have enough studies which have applied these changes to sufficiently large numbers of workers to determine their effectiveness unequivocally. Similar comments apply to administrative interventions. There are a number of more robust experimental designs used in the assessment of behavioural and personal interventions. There is some, but limited, evidence for the effectiveness of exercise for reduction of LBP even though variables such as low muscular strength or body joint flexibility have not been convincingly shown to be risk factors, a preponderance of studies showing little effectiveness of education and contradictory evidence for personal equipment such as back belts. For secondary...